This invention generally pertains to frames for all types of eyewear such as vision-correcting eyeglasses, sunglasses, safety glasses and the like. More particularly, this invention is directed to improved temple portions of such frames wherein the bias, hence the pressure, exerted by the temple against the wearer's head may be selectively varied as required to maintain the frame in proper position.
In accordance with conventional eyewear construction, the forward ends of the temples or sidepieces are hinged to the outboard sides of a lens-receiving section of the frame thereby permitting the temples to fold flat against the back of the frame. The temples swing apart sufficiently to permit placement of the frame on the wearer's head so that the lens-receiving section rests on the bridge of the nose and the free ends of the temples extend backwardly above the ears and press against the head.
Eyewear temples are fabricated of many light weight materials such as plastic or metal or a combination thereof. Usually the temples of vision-correcting eyeglasses are somewhat flexible and may be permanently deformed by heating and bending as an incident to professional fitting of frames to individual wearers. Ideally, the temples are fit for general conformity with the sides of the wearer's head while exerting a comfortably light pressure thereon which is sufficient to maintain the frame and the lenses in the optically correct relationship with the wearer's eyes. However, most wearers of corrective eyeglasses find that, after a period of normal usage, the temples spread apart or become sprung due to deformation of the temples or wearing or loosening of the hinges, or both, whereby the optimum fitted pressure between the head and the temples is diminished. In this instance, the frame will slip forwardly and downwardly along the nose causing the wearer to reposition the frame on the bridge of the nose in a repetitious manner. Such unwanted frame slippage relative to the head irritates the underlying skin and causes eye strain due to periodic actuation of eye focusing muscles in response to the movement of the lenses in front of the eyes.
The aforementioned problems attending frame slippage are exacerbated in the event that the wearer must lean forwardly and downwardly to perform certain tasks and where head movements are started and stopped in a rapid, jerky fashion as, for example, during certain athletic activities.
Eyewear which comprise off-the-shelf articles rather than professionally fitted prescription glasses usually exhibit poorly fitting temples causing considerable slippage and dislocation. This is generally the case with special purpose, non-corrective eyewear which is worn on an as-needed basis to protect the wearer's eyes form outdoor sunlight or from various hazardous conditions found in industrial plants and the like. Even should a choice of sizes be available, wearers of relatively inexpensive sunglasses and temporary safety glasses required in hazardous work areas generally experience temple-to-head pressures which fail to keep the eyewear consistantly in place or which compresses the wearer's head in an uncomfortable manner.
Heretofore it has been proposed to attach a spring device to the frame structure for biasing the temples relative to the lens-carrying portion of the frame in a manner which will urge the temples to pivot about their hinges toward their folded position. The general purpose of such spring biasing means is to create pressure between the temples and the head whereby such pressure in new eyewear automatically adjusts the temples to the head for a good fit or whereby enhanced temple pressure is provided for old eyewear to offset the loss of such pressure due to hinge wear or temple deformation. U.S. Pat. No. 3,923,384 issued on Dec. 2, 1975 to Leblanc discloses a leaf spring biasing means riveted to the temple of the frame wherein the spring coacts with the adjacent corner of the lens bearing portion of the frame to flex the spring as the temples are pivoted toward their open position. Leblanc claims that such spreading and spring flexure produce a reactive force which provides a pressure fit of the temples against the head of the wearer. Similar auxiliary means for spring loading eyewear temples in response to spreading the temples are proposed in U.S. Pat. No. 3,600,068 issued on August, 1971 to Jolicoeur and U.S. Pat. No. 3,654,376 issued Apr. 4, 1972 to Lyons. However, none of these prior art biasing devices provides for wearer adjustment of the temple pressure against the head in the event that the initial spring force fails to produce an acceptable temple-to-head fit or should such auxiliary spring force diminish or become inconsistant due to wearing or bending of the spring component and coacting parts of the frame. Thus this approach to the problem of eyewear slippage appears to be incomplete and, at best, provides only a temporary solution.
Another undesirable limitation of nonadjustable temple biasing means is that the wearer cannot vary selectively the pressure of the temples against the head as needed to meet changing levels or degrees of head motion and acceleration. For example, the need to increase quite substantially temple pressure may arise only during sporadic periods of wearer activity involving rapid or violent head movement which tends to dislodge his eyewear frames. When such activities cease, it is desirable that the temple pressure be readily abated to a point where the temples are held securely against the head without being uncomfortably tight. This advantageous characteristic of eyewear temples would be appreciated by workers who encounter unavoidable head vibration and by athletes during such activities as tennis, basketball and the like.
U.S. Pat. No. 3,479,110 issued Nov. 18, 1969 to Fromm and U.S. Pat. No. 4,204,749 issued May 27, 1980 to Davis propose adjustable auxiliary means for urging eyewear temples into contact with the wearer's head.
Davis shows a pair of structurally complex braces hinged to the lens-carrying portion of the frame. The braces mount protruding thumbscrews which are in bearing contact with the temples. By selectively rotating the thumbscrews, threaded shanks of the same thrust against coacting temples to bias them toward the wearer's head. Davis states that, with the eyeglasses in place, the wearer can adjust the thumbscrews, hence the pressure of the temples against his head, with precision and without the assistance of an optician.
Fromm discloses temples in which the downturned free ends located behind the ears are split to form inner and outer leaves, the outer leaf being relatively rigid and the inner leaf is flexible and adjustable with respect to the outer leaf to press against the wearers head when a wedging ring slidably carried by the outer leaf is pushed therealong to cause deflection of the inner leaf. Fromm states that his temple modification provides adjustable pressure but eliminates the need to bend the temple as a whole and also eliminates the constant pressure created by deforming the temples so as to bear against the wearer's head.
While the aforedescribed auxiliary temple biasing devices suggested by Davis and Fromm display a degree of adjustability, both depend entirely on the resilience of the temple material per se to flex the temple away from the head when the user desires to reduce the temple-to-head pressure for any of the reasons mentioned hereinabove. It is believed that such alternate bending and staightening of conventionally constructed eyewear temples could lead to permanent deformation or even early breakage.
Other disadvantages features of the Davis and Fromm devices are that both the Davis thumbscrew and the Fromm adjusting ring are completely separable from their frames and could be easily lost or misplaced. Both devices produce additional catch points for the wearer's hair and the adjusting means of both detract from the aesthetic appearance of their respective temples.
In general and in the cases of the abovementioned devices in particular, temple biasing means tend to comprise various devices and mechanisms which are auxiliary to and mounted upon the temples and/or the lens-carrying portion of the eyewear frames. This tendency of the prior art to add on expedient structure to conventional temples tends to produce a final article which is generally make-shift in function and appearance.